Featured Research

from universities, journals, and other organizations

Crash-testing rivets for better reliability

Date:
August 7, 2014
Source:
Fraunhofer-Gesellschaft
Summary:
Rivets have to reliably hold the chassis of an automobile together -- even if there is a crash. Previously, it was difficult to predict with great precision how much load they could tolerate. A more advanced model now delivers realistic projections.

A punch-riveted joint fails under bending load: the red areas were particularly seriously deformed.
Credit: Fraunhofer IWM

Rivets have to reliably hold the chassis of an automobile together -- even if there is a crash. Previously, it was difficult to predict with great precision how much load they could tolerate. A more advanced model now delivers realistic projections.

Related Articles


Steel, aluminum, magnesium, fiber-reinforced plastics: cars are built from a wide array of materials today. These have to be connected with each other reliably. To wit: even if the joints become loose in a crash, passengers must face no greater risk of injury than before. Manufacturers use their welding equipment for cars made entirely of steel. However, if you want to combine steel together with aluminum, for example, or steel with plastic materials, then conventional welding techniques are entirely unsuited, plain and simple. Automakers therefore resort to mechanical connections instead, such as rivets.

Very often, connections are the weak points: in a crash, they are typically the first thing to fail. And since a car has about 3,000 to 5,000 joints, manufacturers strive to minimize this risk. This is why automakers use simulations to verify if the various connection points sustain these stresses in an accident. Yet how stable are they in the first place? In many cases, the calculations can clearly predict how the individual joining points will perform, but not for every type of strain, though. If the joined components become bent (experts refer to this as a "flexural load" or "bending load"), then the simulations are quite often off the mark. For example, such computations could ascribe a greater load capacity than the rivets can actually bear under real emergency conditions. This uncertainty is something automakers greatly wish to eliminate.

Realistic projections through a new model

Researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg -- working together with their colleagues from the Laboratory for Material and Joining Technology LWF in Paderborn, and the Association for the Advancement of Applied Computer Science GFaI in Berlin -- have essentially eliminated this drawback now, at least in the simulations."We have further engineered a model that allows us to forecast rivet performance more reliably -- both with slow and fast bending loads, as well as with pull and shear forces that emerge when the joined components become shifted, relative to each other," explains Dr. Silke Sommer, Group Manager at IWM. For this purpose, researchers produced individual "sample components" from a variety of materials, connected them with rivets, and then applied stress. They bent them in a variety of directions, and pulled them and pushed them at varying speeds. They then integrated the performance of the rivet points into the mathematical equations."These equations contain various parameters -- to account for the different materials and their densities, for instance," Sommer says. The researchers at IWM and LWF studied about 15 different combinations of materials. Based on these data, their colleagues at GFaI prepared projections for other similar material and density combinations.

If car manufacturers now want to calculate how the rivets perform in the event of an accident, then as a rule, they simulate the crash first. What forces appear at which points on the car? If these data are known, then the engineers can determine -- for each rivet -- whether it could withstand the strains at precisely this point or in that position. The model is finished and automakers can already use it, and therefore make their cars even safer than before.


Story Source:

The above story is based on materials provided by Fraunhofer-Gesellschaft. Note: Materials may be edited for content and length.


Cite This Page:

Fraunhofer-Gesellschaft. "Crash-testing rivets for better reliability." ScienceDaily. ScienceDaily, 7 August 2014. <www.sciencedaily.com/releases/2014/08/140807105041.htm>.
Fraunhofer-Gesellschaft. (2014, August 7). Crash-testing rivets for better reliability. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2014/08/140807105041.htm
Fraunhofer-Gesellschaft. "Crash-testing rivets for better reliability." ScienceDaily. www.sciencedaily.com/releases/2014/08/140807105041.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. Video provided by Newsy
Powered by NewsLook.com
How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins